Transcript The Immune System Concept 43.1- In innate immunity, recognition

The Immune System
Concept 43.1- In innate immunity, recognition
and response rely on shared traits of pathogens
DION KEVIN
LUKE LEARY
RACHAEL-CATHERINE HARTNETT
Introductory Video
 http://www.cleanvideosearch.com/media/action/yt/
watch?v=Nw27_jMWw10
Overview
 Pathogens- infectious agents that cause disease
 Ex: viruses, bacteria, protists, and fungi
 Immune system- the defenses which enable an
animal to avoid or limit many infections
 Innate immunity- the immediate and
undifferentiated immune response in animals
 Acquired immunity- immune responses which are
specific to pathogens which have already been
introduced
Innate immunity of Invertebrates
 Insects rely on the chitin in their exoskeletons as well
as in their intestines for the first line of defense
 Lysozyme, an enzyme that digests microbial cell
walls, as well as low pH in digestive system aid in the
first line of defense
 Hemocytes, immune cells in insect blood
(hemolymph), carry out phagocytosis
 Other hemocytes stimulate chemical production and
antimicrobrial peptide production
Phagocytosis
Innate Immunity of Invertebrates cont.
 Antimicrobial peptides circulate and disrupt the
membranes of fungi and bacteria
 Immune response cells rely on identification of
unique molecules on invader surface layers
 Ex: pg 932
Innate Immunity of Vertebrates
 Barrier defenses-Barrier defenses are the typical
front line against pathogens.
 Skin, Mucous membranes, tears, etc.
 Beyond the role of blocking pathogens from the body
many create a pathogen killing environment for
toxins.
Innate Immunity Cont.
 Cellular Innate defenses
1.
2.
3.
4.
5.
Toll-like receptors-recognizes molecule fragments of
pathogens
Neutrophils- phagocytic cells which engulf pathogens
Macrophages- Large phagocytic cells which engulf
pathogens efficiently. Most common in lymphatic
organs
Eosinophils-fight multiple cell invaders such as
parasites. Release enzymes to kill invaders
Dendritic Cells-stimulate tissues to develop an
acquired immunity
Innate immunity cont.
 Peptides and proteins work to fight and destroy
pathogens.
 The body fights pathogens in many other ways such
as through inflammation Natural Killer cells.
Innate Immune System Evasion by Pathogens
 Several pathogens have developed certain mechanisms
that allow them to avoid destruction by pathogenic cells.
 In order to do this, for example, the outer capsule that
surrounds the bacteria hides the polysaccharides of their
cell walls, which prevents recognition.
 However, for bacteria that are unable to avoid
recognition, some develop resistanceto breakdown by
lysosomes. An example of this is Tuberculosis(TB).
Instead of being destroyed, microbes grow and
reproduce, hidden from immune defenses of the body.